Relationship between lower limb muscle strength and single-leg sit-to-stand performance in young adults

Abstract

Objective: The purpose of this study was to determine the appropriate protocol of the single-leg sit-to-stand (STS) test in terms of number of repetitions for assessment of the lower limb muscle strength in young adults by exploring relationship between variables obtained from the 1, 3 and 5 repetitions single-leg STS tests (time to complete and power index of the STS test) and lower limb muscle strength obtained from an isokinetic dynamometer.

Materials and methods: Forty-six healthy participants with mean age of 21.04±1.21 years participated in the study. Each participant performed 1, 3, and 5 repetitions of single-leg STS test. Time (T1-STS, T3-STS and T5-STS) and power index (P1-STS, P3-STS and P5-STS) were measured during each repetition of the single-leg STS test. Lower limb muscle strength was measured by a Contrex MJ isokinetic dynamometer.

Results: The intraclass correlation coefficients (ICC3, 1) values of the time to complete the 1, 3 and 5 repetitions single-leg STS test were 0.68, 0.78 and 0.90, respectively. P3-STS and P5-STS were highly correlated with lower limb muscle strength (r=0.753 and r=0.782, respectively) while P1-STS was moderately correlated with lower limb muscle strength (r=0.687). T1-STS, T3-STS and T5-STS had poor to moderate correlations with lower limb muscle strength (r=-0.459, r=-0.487, and r=-0.573, respectively).

Conclusion: Power index of the single-leg STS test had strong relationship to the lower limb muscle strength. Therefore, the power index obtained from single-leg STS test can be used to predict strength of the lower limb muscles. The most suitable number of repetitions when performing the single-leg STS test was 3 repetitions as it required less time to administer and has excellent reliable.